The prior art is replete with structural arrangements for connecting seating portions and back supporting portions to pedestal assemblies. Historically, the seating portion of an office chair was fixedly secured to the upper end portion of a pedestal assembly. The back supporting portion was sometimes also rigidly secured to either the pedestal assembly or the seating portion, and sometimes the back supporting portion was permitted to swing rearwardly, to at least some predetermined degree, in order to permit the person seated in the chair to lean back against the resistance of a biasing mechanism incorporated between the back supporting portion and either the pedestal assembly or the seating portion.
Eventually office seating manufacturers also mounted the seating portion to the pedestal assembly with mechanism that would permit selective rearward tilting of the seating portion. In such constructions the seating portion was generally mounted on pivot axles presented from the pedestal assembly, with variously adjustable spring means being utilized to provide the desired resistance to the tilting action of the seating portion. Here, too, the back supporting portion was initially disposed to be fixed in relation to the seating portion. As the construction of office chairs was refined, the back supporting portion was permitted to swing with respect to the seating portion, but generally only in synchronized relation to the tilting movement of the seating portion. For example, if the seating portion were permitted to tilt through a fixed number of degrees, the back supporting portion was permitted to be swung only a given number of degrees in relation to the number of degrees through which the seating portion was tilted. Hence, when the seating portion was tilted, the back support would generally swing through an incremental range that was mathematically fixed in relation to each degree through which the seating portion was being tilted.
Moreover, in those prior art arrangements wherein the back supporting portion was permitted to swing with respect to the seating portion, the axis about which the back supporting portion was permitted to swing was generally located in proximity to the rear of the seating portion. As such, when the person seated in the chair leaned back, the back supporting portion would "scrub" against the clothing being worn by the person seated in the chair. Although this scrubbing action was not serious, during the course of several hours the shirt, or blouse, being worn by the person using the chair could be extricated from the mere frictional support by which it was held at the waist.
Over the years adjustments to the spring action against which the person could tilt the seating portion, and/or swing the back supporting portion, were included. However, it was generally a rather tedious operation to effect the desired adjustment to the resistance provided by the springs.